CN100546420C - Light source driving circuit - Google Patents
Light source driving circuit Download PDFInfo
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- CN100546420C CN100546420C CNB200610159861XA CN200610159861A CN100546420C CN 100546420 C CN100546420 C CN 100546420C CN B200610159861X A CNB200610159861X A CN B200610159861XA CN 200610159861 A CN200610159861 A CN 200610159861A CN 100546420 C CN100546420 C CN 100546420C
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Abstract
The invention discloses a kind of light source driving circuit, in order to drive a light-emitting component.This light source driving circuit comprises power supply circuit, light adjusting circuit and feedback circuit.First end of light adjusting circuit couples an end of light-emitting component, and its second termination is received the supply voltage that power supply circuit is exported.Light adjusting circuit determines the conducting state of its first end and its second end according to the logic state of a pulse width signal.Feedback circuit is coupled between the feedback end of first end of light adjusting circuit and power supply circuit.Feedback circuit is controlled the level of the supply voltage that power supply circuit exports according to the conducting state of light adjusting circuit.According to above-mentioned, this light source driving circuit can avoid light adjusting circuit to be punctured by too high voltage.
Description
Technical field
The present invention is relevant for a kind of drive circuit, and is particularly to a kind of light source driving circuit of driven light-emitting element.
Background technology
Light source driving circuit is widely used in the various display unit, light-emitting diode (LED) drive circuit of for example backlight liquid crystal display drive circuit, or hand-hold type mobile device.Because display unit is seen in day by day in the electronic product of various kinds, so light source driving circuit just has the development potentiality of height.Wherein there are many advantages to be enhanced constantly and to promote, comprise that energy conversion efficiency increases, stability promotes or the like.
Existing framework in order to the light source driving circuit that drives a light emitting diode string 101 as shown in Figure 1, wherein light emitting diode string 101 is made up of the light-emitting diode 102 of a plurality of serial connections.This conventional lighting sources drive circuit comprises DC-DC power supply converter 103, electric capacity 104, output voltage feedback circuit 105, sequential control circuit 106 and light adjusting circuit 107.Wherein light adjusting circuit 107 is coupled between the negative electrode and common electric potential GND of light emitting diode string 101, and receives the pulse width signal PWM that sequential control circuit 106 is exported.In addition, output voltage feedback circuit 105 utilizes the resistance of two series connection, is respectively 108 and 109 and implements.
DC-DC power supply converter 103 supplying DC power source voltages are given light emitting diode string 101, and carry out FEEDBACK CONTROL and output DC source voltage stably according to the feedback signal FB that output voltage feedback circuit 105 received.Sequential control circuit 106 determines the width of the pulse width signal PWM that it is exported according to the brightness that the user sets.Conducting when light adjusting circuit 107 is in high potential at pulse width signal PWM, and when pulse width signal PWM is in electronegative potential, close.See through the width of adjusting pulse width signal PWM, just can control the conducting state of light adjusting circuit 107, whether flow through electric current to control light emitting diode string 101 further.
So, when setting brightness when brighter, it is longer that pulse width signal PWM presents time of high potential, make the ON time of light adjusting circuit 107 longer, thereby the brightness of light emitting diode string 101 is also brighter.Otherwise when setting brightness was dark, it is shorter that pulse width signal PWM presents the time of high potential, make the ON time of light adjusting circuit 107 shorter, thereby the brightness of light emitting diode string 101 is also darker.
Yet, when pulse width signal PWM is in electronegative potential, light adjusting circuit 107 is closed (being the negative electrode of light emitting diode string 101 and the not conducting of electrical path between the common electric potential GND), and this moment, the pressure drop of the DC power supply voltage that DC-DC power supply converter 103 is supplied all dropped on the light adjusting circuit 107.When a lot of light-emitting diode 102 of light emitting diode string 101 series connection, the magnitude of voltage of the DC power supply voltage that DC-DC power supply converter 103 is supplied will be very high.
In in the case, if light adjusting circuit 107 is withstand voltage not enough, the DC power supply voltage that will cause light adjusting circuit 107 to be supplied by DC-DC power supply converter 103 punctures, and causes light adjusting circuit 107 damages.In addition, also may therefore need to use withstand voltage higher light adjusting circuit 107, yet, withstand voltage higher light adjusting circuit 107 certainly will need bigger volume and higher price, except the volume that may increase integrated circuit, more increase the cost of circuit, also therefore reduced the competitiveness of product on market.
Summary of the invention
Purpose of the present invention is providing a kind of light source driving circuit exactly, in order to reduce the voltage that light adjusting circuit bore, is damaged by too high voltage to prevent light adjusting circuit, and then prolongs the useful life of light source driving circuit.
A further object of the present invention provides a kind of light source driving circuit, in order to lower the cost of light source driving circuit inner member, to reach the increase product competitiveness.
According to above-mentioned and other purpose, the present invention proposes a kind of light source driving circuit, and in order to drive first light-emitting component, a wherein end of first light-emitting component couples first voltage.This light source driving circuit comprises first light adjusting circuit, power supply circuit and feedback circuit.Wherein first light adjusting circuit has first end, second end and pulse width signal input, its first end couples the other end of first light-emitting component, its pulse width signal input receives pulse width signal, and first light adjusting circuit determines the conducting state between its first end and its second end according to the logic state of pulse width signal.
Power supply circuit has output and feedback end, its output couples second end of first light adjusting circuit, in order to supply second end that second voltage is given first light adjusting circuit, and power supply circuit determines the value of second voltage according to the feedback signal that its feedback end received, and wherein second voltage is less than first voltage.Feedback circuit is coupled between the feedback end of first end of first light adjusting circuit and power supply circuit, in order to determine the value of feedback signal according to the conducting state of first light adjusting circuit.
According to the described light source driving circuit of preferred embodiment of the present invention, above-mentioned feedback circuit comprises circuit for detecting and feedback voltage control circuit.Wherein circuit for detecting comprises first end, second end and output, its first end couples first end of first light adjusting circuit, its second end couples common electric potential, in order to the current potential that the output of the decision of the impedance between second end of first end of foundation circuit for detecting and circuit for detecting circuit for detecting is exported, wherein this common electric potential is the earth terminal current potential.The input of feedback voltage control circuit couples the output of circuit for detecting, its output output feedback signal, and in order to the current potential that the output of foundation circuit for detecting is exported, Control and Feedback voltage of signals value.
According to the described light source driving circuit of preferred embodiment of the present invention, above-mentioned circuit for detecting comprises first impedance component and second impedance component.A first impedor wherein end, first end that is circuit for detecting wherein, and the other end is the output of circuit for detecting.A second impedor wherein end couples the first impedor other end, and the other end is second end of circuit for detecting.
According to the described light source driving circuit of preferred embodiment of the present invention, above-mentioned feedback voltage control circuit comprises operational amplifier, it comprises first input end, second input and output, its first input end couples the output of circuit for detecting, its second input couples reference voltage, and its output couples the feedback end of power supply circuit.In an embodiment, the feedback voltage control circuit also comprises first diode and the 3rd impedance component.Wherein the negative electrode of first diode couples the output of operational amplifier, and its anode couples the feedback end of power supply circuit.The 3rd impedance component is coupled between the output of the negative electrode of first diode and operational amplifier.
According to the described light source driving circuit of preferred embodiment of the present invention, above-mentioned feedback circuit also comprises the output voltage feedback circuit.The output voltage feedback circuit is coupled between the feedback end of the output of power supply circuit and power supply circuit, in order to the magnitude of voltage according to second voltage decision feedback signal.In an embodiment, the output voltage feedback circuit comprises the 4th impedance component and the 5th impedance component.Wherein the 4th an impedor wherein end couples the output of power supply circuit, and its other end couples the feedback end of power supply circuit.The 5th an impedor wherein end couples the 4th impedor other end, and its other end couples common electric potential.
According to the described light source driving circuit of preferred embodiment of the present invention, it also comprises sequential control circuit.Sequential control circuit couples the pulse width signal input of first light adjusting circuit, in order to the brightness settings that the user imported, is converted to pulse width signal.
According to the described light source driving circuit of preferred embodiment of the present invention, it also comprises level lifting circuit.Level lifting circuit is coupled between the pulse width signal input of the sequential control circuit and first light adjusting circuit, in order to receiving the pulse width signal that sequential control circuit is exported, and exports after the level with pulse width signal promotes.
Light source driving circuit of the present invention receives a supply voltage for second end (being earth terminal) with its light adjusting circuit, and adjust the level of supply voltage adaptively by the conducting state of light adjusting circuit, to reduce the voltage that light adjusting circuit was born, make light adjusting circuit avoid being punctured by too high voltage, therefore can prevent that the light source driving circuit inner member from damaging, prolong the useful life of light source driving circuit, and also make light source driving circuit needn't adopt high withstand voltage light adjusting circuit, lower the cost of light source driving circuit inner member, reached the increase product competitiveness.
For above-mentioned and other purposes, feature and advantage of the present invention can be become apparent, preferred embodiment cited below particularly, and conjunction with figs. is described in detail below.
Description of drawings
Fig. 1 is the Organization Chart of conventional lighting sources drive circuit.
Fig. 2 is the circuit diagram according to the light source driving circuit of one embodiment of the invention.
Fig. 3, Fig. 4, Fig. 5, Fig. 6 are the circuit diagram according to the light source driving circuit of another embodiment of the present invention.
Embodiment
Fig. 2 is the circuit diagram according to the light source driving circuit of one embodiment of the invention.Please refer to Fig. 2, this light source driving circuit is in order to driven light-emitting element 201, and a wherein end of light-emitting component 201 couples the first voltage VLED.Light-emitting component 201 can be a light-emitting diode, as Fig. 2 202 shown in, also can be the light emitting diode string that forms by a plurality of light-emitting diodes 202 serial connections, or the light-emitting component of other patterns/light-emitting component string.This light source driving circuit comprises light adjusting circuit 203, power supply circuit 204 and feedback circuit.
When setting brightness when brighter, it is longer that pulse width signal PWM presents time of high potential, make the ON time of light adjusting circuit 203 longer, thereby the brightness of light emitting diode string 201 is also brighter.Otherwise when setting brightness was dark, it is shorter that pulse width signal PWM presents the time of high potential, make the ON time of light adjusting circuit 203 shorter, thereby the brightness of light emitting diode string 201 is also darker.
In this embodiment, pulse width signal PWM is provided by sequential control circuit 205.Sequential control circuit 205 is converted to pulse width signal PWM in order to the brightness settings that the user imported.And this embodiment also between the pulse width signal input of sequential control circuit 205 and light adjusting circuit 203, adopts a level lifting circuit 206 more.Level lifting circuit 206 is in order to receiving the pulse width signal PWM that sequential control circuit 205 is exported, and exports to the pulse width signal input of light adjusting circuit 203 after the level with pulse width signal PWM promotes.Yet level lifting circuit 206 is the usefulness for the level that promotes pulse width signal PWM, so the user can do increase and decrease according to actual needs.
In this embodiment, feedback circuit comprises circuit for detecting 207, feedback voltage control circuit 208 and output voltage feedback circuit 209.Wherein circuit for detecting 207 comprises first end, second end and output, its first end couples first end of light adjusting circuit 203, its second end couples common electric potential GND, the current potential of exporting in order to the output of the decision of the impedance between second end of first end of foundation circuit for detecting 207 and circuit for detecting 207 circuit for detecting 207.
The input of feedback voltage control circuit 208 couples the output of circuit for detecting 207, its output output feedback signal FB, and in order to the current potential that the output of foundation circuit for detecting 207 is exported, the magnitude of voltage of Control and Feedback signal FB.Output voltage feedback circuit 209 is coupled between the feedback end of the output of power supply circuit 204 and power supply circuit 204, in order to the magnitude of voltage according to second voltage VFG decision feedback signal FB.
Circuit for detecting 207 comprises first impedance component and second impedance component.A first impedor wherein end, first end that is circuit for detecting 207 wherein, and the other end is the output of circuit for detecting 207.A second impedor wherein end couples the first impedor other end, and the other end is second end of circuit for detecting 207.First impedance component of this embodiment and second impedance component are realized with resistance 210 and 211 respectively.
Feedback voltage control circuit 208 comprises operational amplifier 212, diode 213 and the 3rd impedance component.Operational amplifier 212 comprises first input end, second input and output, and its first input end couples the output of circuit for detecting 207, and its second input couples reference voltage VREF.The 3rd impedance component is coupled between the negative electrode of the output of operational amplifier 212 and diode 213.The anode of diode 213 couples the feedback end of power supply circuit 204.In this embodiment, the 3rd impedance component realizes with resistance 214, and the first input end of operational amplifier 212 is negative input end, and second input of operational amplifier 212 is a positive input terminal.
Output voltage feedback circuit 209 comprises the 4th impedance component and the 5th impedance component.The 4th an impedor wherein end couples the output of power supply circuit 204, and its other end couples the feedback end of power supply circuit 204.The 5th an impedor wherein end couples the 4th impedor other end, and its other end couples common electric potential GND.In this embodiment, the 4th impedance component and the 5th impedance component are realized with resistance 215 and 216 respectively.
When pulse width signal PWM is low logic state, light-emitting component 201 extinguishes, the voltage that first end of light adjusting circuit 203 is born can rise, but when not reaching light adjusting circuit 203 maximum withstand voltage as yet, resistance 211 resulting partial pressure value in the circuit for detecting 207 are just greater than the value of the operational amplifier 212 reference voltage VREF that receives, therefore operational amplifier 212 is output as low logic state (being the output earthed voltage at this embodiment), make diode 213 conductings, cause resistance 214 in parallel with resistance 216, make the feedback signal that feedback end received of power supply circuit 204 diminish, and then make power supply circuit 204 promote the level of the second voltage VFG that its output exports according to its feedback mechanism.
Therefore, the voltage that born of first end of light adjusting circuit 203 conveniently becomes the first voltage VLED and deducts the resulting value of the second voltage VFG.Thus, light adjusting circuit 203 just can not punctured by the first too high voltage VLED.
When pulse width signal PWM is high logic state, light-emitting component 201 is lighted, resistance 211 resulting partial pressure value in the circuit for detecting 207 are with regard to the magnitude of voltage of the less-than operation amplifier 212 reference voltage VREF that receives at this moment, therefore operational amplifier 212 is output as high logic state, make diode 213 not conductings, so the feedback signal that feedback end received of power supply circuit 204 is resistance 209 resulting dividing potential drops, and then make power supply circuit 204 export the second voltage VFG of normal level according to its feedback mechanism.
Therefore, the second voltage VFG that power supply circuit 204 is exported when pulse width signal PWM is high logic state, it is low that the second voltage VFG that can be exported when pulse width signal PWM is low logic state than power supply circuit 204 also comes, just meet light adjusting circuit 203 when pulse width signal PWM is low logic state, second voltage that needs higher level, with first end and the voltage difference between second end that lowers light adjusting circuit 203, so can guarantee that more light adjusting circuit 203 avoids being punctured by the first too high voltage VLED at this moment.Certainly, second end (being earth terminal) that also can be considered light adjusting circuit 203 of above-mentioned action is coupled to a floating earth (Floating Ground) current potential.
Shown in the embodiment of Fig. 2, the present invention also can adopt a plurality of light adjusting circuits in light source driving circuit, to drive a plurality of light-emitting components.Below will be that example illustrates the present invention with the light source driving circuit that drives two light-emitting components, as shown in Figure 3.
Fig. 3 is the circuit diagram according to the light source driving circuit of another embodiment of the present invention.Please refer to Fig. 2 and Fig. 3, to distinguish not existing together of Fig. 2 and Fig. 3 according to explanation.Circuit shown in Figure 3 is that circuit shown in Figure 2 is added light-emitting component 301 and light adjusting circuit 302, and forms one in order to drive the light source driving circuit of two light-emitting components.Wherein light-emitting component 301 can be identical with light-emitting component 201, and the function of light adjusting circuit 302 is also the same with light adjusting circuit 203 with mode of operation.For Fig. 2, Fig. 3 has only increased light-emitting component 301 and light adjusting circuit 302, so Fig. 3 is identical with the operating principle of Fig. 2, do not repeat them here, right this area has knows that usually the knowledgeable should know by inference easily, and example shown in Figure 3 is as if using the multi-group light-emitting element and organizing light adjusting circuit more and also can implement.
Circuit shown in Figure 3, only come light adjusting circuit 203 is carried out Voltage Feedback with circuit for detecting 207, yet the user can all do Voltage Feedback to all light adjusting circuits of the present invention, so that feedback voltage control circuit 208 can remove the magnitude of voltage of Control and Feedback signal FB according to the conducting state of each light adjusting circuit, and then adjust the level of second voltage that power supply circuit 204 exported.Below be that example illustrates another embodiment of the present invention with another one in order to the light source driving circuit that drives two light-emitting components, as shown in Figure 4.
Fig. 4 is the circuit diagram according to the light source driving circuit of another embodiment of the present invention.Please refer to Fig. 3 and Fig. 4, to distinguish not existing together of Fig. 3 and Fig. 4 according to explanation.Circuit shown in Figure 4 is with diode 401 of the many again employings of the circuit for detecting among Fig. 3 207, to form circuit for detecting 402.And the circuit for detecting 403 that function of the more employings of circuit shown in Figure 4 and circuit for detecting 402 are the same, wherein circuit for detecting 403 comprises resistance 404 and 405 and diode 406.Thus, the current potential that feedback voltage control circuit 208 just can be exported according to the output of circuit for detecting 402, and the current potential exported of the output of circuit for detecting 403, and remove the magnitude of voltage of Control and Feedback signal FB, and then adjust the level of second voltage that power supply circuit 204 exported.
Because Fig. 4 can be considered the enforcement kenel of deriving out according to circuit shown in Figure 3, for circuit shown in Figure 3, first end that circuit shown in Figure 4 only increases light adjusting circuit 302 carries out Voltage Feedback, so Fig. 4 is also identical with the operating principle of Fig. 2, do not repeat them here, right this area has knows that usually the knowledgeable should know by inference easily, and example shown in Figure 4 is as if using the multi-group light-emitting element and organizing light adjusting circuit more and also can implement.
Shown in Fig. 3 embodiment, the present invention can also change light adjusting circuit shown in Figure 3 203 and 302 employing and have a plurality of inputs light adjusting circuit of (promptly containing a plurality of passages), so that each light adjusting circuit can drive a plurality of light-emitting components simultaneously.Below will be that example illustrates the present invention with the light source driving circuit that drives four light-emitting components, as shown in Figure 5.
Fig. 5 is the circuit diagram according to the light source driving circuit of another embodiment of the present invention.Please refer to Fig. 3 and Fig. 5, to distinguish not existing together of Fig. 3 and Fig. 5 according to explanation.Light source driving circuit shown in Figure 5 is in order to driven light-emitting element 201, light-emitting component 301, light-emitting component 501 and light-emitting component 502.Fig. 5 changes the light adjusting circuit 503 that employing has first end, second end, the 3rd end and pulse width signal input with light adjusting circuit shown in Figure 3 203, and light adjusting circuit shown in Figure 3 302 is changed the light adjusting circuit 504 that employing has first end, second end, the 3rd end and pulse width signal input equally.
First end of light adjusting circuit 503 is in order to couple light-emitting component 201, second end of light adjusting circuit 503 is in order to couple common electric potential GND, the 3rd end of light adjusting circuit 503 is in order to couple light-emitting component 501, and the pulse width signal input of light adjusting circuit 503 is in order to receive pulse width signal PWM.First end of light adjusting circuit 504 is in order to couple light-emitting component 301, second end of light adjusting circuit 503 is in order to couple common electric potential GND, the 3rd end of light adjusting circuit 503 is in order to couple light-emitting component 502, and the pulse width signal input of light adjusting circuit 503 is in order to receive pulse width signal PWM.
The logic state of the pulse width signal PWM that light adjusting circuit 503 and light adjusting circuit 504 are all received according to its pulse width signal input determines the conducting state between its first end and its second end, with and the 3rd end and its second end between conducting state.With this embodiment, when pulse width signal is high logic (high potential) state, first end of light adjusting circuit 503 and the electrical path between second end, and the 3rd electrical path between end and second end be conducting, and first end of light adjusting circuit 504 and the electrical path between second end, and the 3rd electrical path between end and second end also be conducting, otherwise then neither conducting.
Because Fig. 5 also can be considered the enforcement kenel of deriving out according to circuit shown in Figure 3, for circuit shown in Figure 3, circuit shown in Figure 5 only changes the original light adjusting circuit of Fig. 3 the light adjusting circuit that employing has many inputs, so Fig. 5 is also identical with the operating principle of Fig. 2, do not repeat them here, right those of ordinary skills should know by inference easily, and example shown in Figure 5 is if use multi-group light-emitting element and the light adjusting circuit with many inputs of organizing also can be implemented more.In addition, example shown in Figure 5 is if use single light adjusting circuit and the multi-group light-emitting element with many inputs can implement too.
Shown in Fig. 4 and Fig. 5 embodiment, the user also can all do Voltage Feedback with first end and the 3rd end of the light adjusting circuit among Fig. 5 503 and 504, as shown in Figure 6.
Fig. 6 is the circuit diagram according to the light source driving circuit of another embodiment of the present invention.Please refer to Fig. 5 and Fig. 6, to distinguish not existing together of Fig. 5 and Fig. 6 according to explanation.Circuit shown in Figure 6 is with diode 601 of the many again employings of the circuit for detecting among Fig. 5 207, to form circuit for detecting 602.And three functions of the more employings of circuit shown in Figure 6 and structure be the same circuit for detecting 603,604 and 605 with circuit for detecting 602 all.
Wherein first end of circuit for detecting 603 couples first end of light adjusting circuit 504, and second end of circuit for detecting 603 couples common electric potential GND, and the output of circuit for detecting 603 couples the first input end of operational amplifier 212.First end of circuit for detecting 604 couples the 3rd end of light adjusting circuit 503, and second end of circuit for detecting 60 couples common electric potential GND, and the output of circuit for detecting 604 couples the first input end of operational amplifier 212.First end of circuit for detecting 605 couples the 3rd end of light adjusting circuit 504, and second end of circuit for detecting 605 couples common electric potential GND, and the output of circuit for detecting 605 couples the first input end of operational amplifier 212.
Thus, the current potential that the current potential that the output of the current potential that feedback voltage control circuit 208 just can be exported according to the output of circuit for detecting 602, current potential that the output of circuit for detecting 603 is exported, circuit for detecting 604 is exported and the output of circuit for detecting 605 are exported, and remove the magnitude of voltage of Control and Feedback signal FB, and then adjust the level of second voltage that power supply circuit 204 exported.
Because Fig. 6 can be considered the enforcement kenel of deriving out according to circuit shown in Figure 5, for circuit shown in Figure 5, circuit shown in Figure 6 is to first end of light adjusting circuit 503 and the 3rd end, and first end of light adjusting circuit 504 and the 3rd end all carry out Voltage Feedback, so Fig. 6 is also identical with the operating principle of Fig. 2, do not repeat them here, right those of ordinary skills should know by inference easily, and example shown in Figure 6 is if use multi-group light-emitting element and the light adjusting circuit with many inputs of organizing also can be implemented more.
Though the various embodiments described above provide multiple possible enforcement kenel to light source driving circuit, yet having, this field knows that usually the knowledgeable should know, each manufacturer is neither the same for the design of light source driving circuit, therefore so long as second end (being earth terminal) of light adjusting circuit is received a supply voltage, and adjust the level of supply voltage adaptively by the conducting state of light adjusting circuit, to reduce the voltage that light adjusting circuit was born, make light adjusting circuit avoid being punctured, just met spiritual place of the present invention by too high voltage.
What deserves to be mentioned is, the power supply circuit of the various embodiments described above is not limited to specific certain power supply circuit, such as voltage-dropping type (Buck), booster type (Boost), buck-boost type (Buck-Boost) power supply circuit and above-mentioned power supply circuit derive various open up benefit for example forward (Forward), return speed (Flyback), half-bridge, full-bridge or the like, also or linear voltage regulator all can be in order to implement embodiments of the invention.
Light source driving circuit of the present invention receives a supply voltage for second end (being earth terminal) with its light adjusting circuit, and adjust the level of supply voltage adaptively by the conducting state of light adjusting circuit, to reduce the voltage that light adjusting circuit was born, make light adjusting circuit avoid being punctured by too high voltage, therefore can prevent that the light source driving circuit inner member from damaging, prolong the useful life of light source driving circuit, and also make light source driving circuit needn't adopt high withstand voltage light adjusting circuit, lower the cost of light source driving circuit inner member, reached the increase product competitiveness.
Though the present invention discloses as above with preferred embodiment; right its is not in order to qualification the present invention, any those of ordinary skills, without departing from the spirit and scope of the present invention; when can doing a little change and retouching, so protection scope of the present invention is when with being as the criterion that claim was defined.
Claims (25)
1. light source driving circuit, in order to drive one first light-emitting component, a wherein end of this first light-emitting component couples one first voltage, and this light source driving circuit comprises:
One first light adjusting circuit, have first end, second end and pulse width signal input, its first end couples the other end of this first light-emitting component, its pulse width signal input receives a pulse width signal, and this first light adjusting circuit determines the conducting state between its first end and its second end according to the logic state of this pulse width signal;
One power supply circuit, have output and feedback end, its output couples second end of this first light adjusting circuit, in order to supply second end that one second voltage is given this first light adjusting circuit, and this power supply circuit determines the value of this second voltage according to the feedback signal that its feedback end received, and wherein this second voltage is less than this first voltage; And
One feedback circuit is coupled between the feedback end of first end of this first light adjusting circuit and this power supply circuit, in order to determine the value of this feedback signal according to the conducting state of this first light adjusting circuit.
2. light source driving circuit as claimed in claim 1 is characterized in that this feedback circuit also is coupled to the output of this power supply circuit, to determine the value of this feedback signal according to this second voltage.
3. light source driving circuit as claimed in claim 1 is characterized in that, this feedback circuit comprises:
One circuit for detecting, comprise first end, second end and output, its first end couples first end of this first light adjusting circuit, its second end couples a common electric potential, in order to determine the current potential that the output of this circuit for detecting is exported according to the impedance between second end of first end of this circuit for detecting and this circuit for detecting, wherein this common electric potential is the earth terminal current potential; And
One feedback voltage control circuit, its input couples the output of this circuit for detecting, and its output is exported this feedback signal, in order to the current potential of being exported according to this circuit for detecting output, controls the magnitude of voltage of this feedback signal.
4. light source driving circuit as claimed in claim 3 is characterized in that, this circuit for detecting comprises:
One first impedance component, one end are first end of this circuit for detecting, and its other end is the output of this circuit for detecting; And
One second impedance component, one end couple this first impedor other end, and its other end is second end of this circuit for detecting.
5. light source driving circuit as claimed in claim 4 is characterized in that, this first impedance component and this second impedance component respectively comprise a resistance.
6. light source driving circuit as claimed in claim 3 is characterized in that, this feedback voltage control circuit comprises:
One operational amplifier, it comprises first input end, second input and output, and its first input end couples the output of this circuit for detecting, and its second input couples a reference voltage, and its output couples the feedback end of this power supply circuit.
7. light source driving circuit as claimed in claim 6 is characterized in that, this feedback voltage control circuit also comprises:
One first diode, its negative electrode couples the output of this operational amplifier, and its anode couples the feedback end of this power supply circuit.
8. light source driving circuit as claimed in claim 7 is characterized in that, this feedback voltage control circuit also comprises:
One the 3rd impedance component is coupled between the output of the negative electrode of this first diode and this operational amplifier.
9. light source driving circuit as claimed in claim 3 is characterized in that, this feedback circuit also comprises:
One output voltage feedback circuit is coupled between the feedback end of the output of this power supply circuit and this power supply circuit, in order to determine the magnitude of voltage of this feedback signal according to this second voltage.
10. light source driving circuit as claimed in claim 9 is characterized in that, this output voltage feedback circuit comprises:
One the 4th impedance component, the one end couples the output of this power supply circuit, and its other end couples the feedback end of this power supply circuit; And
One the 5th impedance component, one end couple the 4th impedor other end, and its other end couples this common electric potential.
11. light source driving circuit as claimed in claim 1 is characterized in that, also comprises:
One sequential control circuit couples the pulse width signal input of this first light adjusting circuit, in order to the brightness settings that the user imported, is converted to this pulse width signal.
12. light source driving circuit as claimed in claim 11 is characterized in that, also comprises:
One level lifting circuit is coupled between the pulse width signal input of this sequential control circuit and this first light adjusting circuit, in order to receiving this pulse width signal that this sequential control circuit is exported, and exports after the level with this pulse width signal promotes.
13. light source driving circuit as claimed in claim 1 is characterized in that, this first light-emitting component is a light-emitting diode, and its anode couples this first voltage.
14. light source driving circuit as claimed in claim 1 is characterized in that, this first light-emitting component is a plurality of light-emitting diodes, and those light-emitting diodes are connected in series in the mode that anode couples negative electrode, and wherein the anode of first light-emitting diode couples this first voltage.
15. light source driving circuit as claimed in claim 1, it is characterized in that, this light source driving circuit is also in order to drive one second light-emitting component, a wherein end of this second light-emitting component couples this first voltage, and this first light adjusting circuit also comprises the 3rd end, the 3rd end of this first light adjusting circuit couples the other end of this second light-emitting component, and this first light adjusting circuit determines the conducting state between its 3rd end and its second end according to the logic state of this pulse width signal.
16. light source driving circuit as claimed in claim 1 is characterized in that, also in order to drive one second light-emitting component, a wherein end of this second light-emitting component couples this first voltage to this light source driving circuit, and this light source driving circuit also comprises:
One second light adjusting circuit, its first end couples the other end of this second light-emitting component, its second end couples a common electric potential, and the pulse width signal input of this second light adjusting circuit couples the pulse width signal input of this first light adjusting circuit, with logic state according to this pulse width signal, determine the conducting state between its first end and its second end, wherein this common electric potential is the earth terminal current potential.
17. light source driving circuit as claimed in claim 16 is characterized in that, this feedback circuit comprises:
One first circuit for detecting, comprise first end, second end and output, its first end couples first end of this first light adjusting circuit, its second end couples this common electric potential, in order to determine the current potential that the output of this first circuit for detecting is exported according to the impedance between second end of first end of this first circuit for detecting and this first circuit for detecting;
One second circuit for detecting, comprise first end, second end and output, its first end couples first end of this second light adjusting circuit, its second end couples this common electric potential, in order to determine the current potential that the output of this second circuit for detecting is exported according to the impedance between second end of first end of this second circuit for detecting and this second circuit for detecting; And
One feedback voltage control circuit, its input couples the output of this first circuit for detecting and this second circuit for detecting, its output is exported this feedback signal, in order to the current potential of exporting according to the output of this first circuit for detecting and this second circuit for detecting, controls the magnitude of voltage of this feedback signal.
18. light source driving circuit as claimed in claim 17 is characterized in that, this first circuit for detecting and this second circuit for detecting comprise respectively:
One first impedance component, one end are first end of this first circuit for detecting;
One second impedance component, one end couple this first impedor other end, and its other end couples this common electric potential;
One first diode, its anode couple this first impedor other end, and its negative electrode couples the output of this first circuit for detecting;
One the 3rd impedance component, one end are first end of this second circuit for detecting;
One the 4th impedance component, one end couple the 3rd impedor other end, and its other end couples this common electric potential; And
One second diode, its anode couple the 3rd impedor other end, and its negative electrode couples the output of this second circuit for detecting.
19. light source driving circuit as claimed in claim 17 is characterized in that, this feedback voltage control circuit comprises:
One operational amplifier, it comprises first input end, second input and output, its first input end couples the output of this first circuit for detecting and the output of this second circuit for detecting, and its second input couples a reference voltage, and its output couples the feedback end of this power supply circuit.
20. light source driving circuit as claimed in claim 19 is characterized in that, this feedback voltage control circuit also comprises:
One the 3rd diode, its negative electrode couples the output of this operational amplifier, and its anode couples the feedback end of this power supply circuit.
21. light source driving circuit as claimed in claim 20 is characterized in that, this feedback voltage control circuit also comprises:
One the 5th impedance component is coupled between the output of the negative electrode of the 3rd diode and this operational amplifier.
22. light source driving circuit as claimed in claim 17 is characterized in that, this feedback circuit also comprises:
One output voltage feedback circuit is coupled between the feedback end of the output of this power supply circuit and this power supply circuit, in order to determine the magnitude of voltage of this feedback signal according to this second voltage.
23. light source driving circuit as claimed in claim 22 is characterized in that, this output voltage feedback circuit comprises:
One the 6th impedance component, the one end couples the output of this power supply circuit, and its other end couples the feedback end of this power supply circuit; And
One the 7th impedance component, one end couple the 6th impedor other end, and its other end couples this common electric potential.
24. light source driving circuit as claimed in claim 16 is characterized in that, this second light-emitting component is a light-emitting diode, and its anode couples this first voltage.
25. light source driving circuit as claimed in claim 16 is characterized in that, this second light-emitting component is a plurality of light-emitting diodes, and those light-emitting diodes are connected in series in the mode that anode couples negative electrode, and wherein the anode of first light-emitting diode couples this first voltage.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB200610159861XA CN100546420C (en) | 2006-10-25 | 2006-10-25 | Light source driving circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB200610159861XA CN100546420C (en) | 2006-10-25 | 2006-10-25 | Light source driving circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN101170850A CN101170850A (en) | 2008-04-30 |
| CN100546420C true CN100546420C (en) | 2009-09-30 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB200610159861XA Expired - Fee Related CN100546420C (en) | 2006-10-25 | 2006-10-25 | Light source driving circuit |
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| Country | Link |
|---|---|
| CN (1) | CN100546420C (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101990337B (en) * | 2009-08-03 | 2014-03-26 | 联咏科技股份有限公司 | Light source drive device capable of dynamically maintaining constant current drive and related method thereof |
| KR101221583B1 (en) | 2009-12-28 | 2013-01-14 | 엘지디스플레이 주식회사 | Back Light Unit, Method for Driving The Same, and Liquid Crystal Display Device Using The Same |
| TWI448188B (en) * | 2010-07-29 | 2014-08-01 | Richtek Technology Corp | Circuit and method for providing absolute information for floating grounded integrated circuit |
| CN102446492A (en) * | 2010-10-08 | 2012-05-09 | 联咏科技股份有限公司 | Short-circuit sensing circuit and method, and driving chip and equipment of light emitting diode |
| CN102467881A (en) * | 2010-11-09 | 2012-05-23 | 联咏科技股份有限公司 | Light-emitting diode (LED) driving device, LED apparatus and driving method thereof |
| CN106601182A (en) * | 2015-10-15 | 2017-04-26 | 帝奥微电子有限公司 | Light-emitting diode backlight drive circuit |
-
2006
- 2006-10-25 CN CNB200610159861XA patent/CN100546420C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CN101170850A (en) | 2008-04-30 |
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